Sources of uncontrolled release of ionizing radiation in industry, transportation and military operations are a major health concern to those responsible for safety in these areas. A number of instruments are available to detect such radiations, and are suitable for use by the armed forces and by civilian rescue operations. Invariably such instruments detect one or more of the various radiations likely to be encountered and have very great sensitivity, enabling exceedingly low levels of contamination to be detected.
Once a radiation hazard has been detected, operations to remove or control the hazard may be set in motion. If the source of the radiation is a piece of solid metal, it may be placed in a container, and likewise for liquids, following absorption into a solid. However, many sources of contamination will take the form of particulate material, e.g. dust, for instance following a fire in a radiochemical laboratory, or fallout onto a vehicle, e.g. a ship, from a nuclear weapon or other explosion. In such cases, washing by use of sprinkler systems or hoses may be used to decontaminate the building or vehicle, an instrument being used to monitor the progress and efficiency of the washing process.
Clearly, very thorough training in these cleaning and monitoring processes is needed to ensure that safe operating procedures are followed. However, no responsible organization will willingly spread radioactive particles or dust in a training situation, and it is thus not feasible to train operators in the use, in all circumstances, of instrumentation which responds to radiation.
It has already been suggested (e.g. in U.S. Pat. Nos. 4,500,295, 3,636,641, WO 89/08905, GB-A-1,311,615 and GB-A-2,209,235) to provide either an electrical or a magnetic system which will mimic radiation in that it will give a non-radioactive radio-frequency, or ultra-sonic or magnetic `signal` that can be detected by an alternative instrument. These systems would appear to have two major drawbacks in that each requires an electrical or magnetic source (which will appear out of context in the training area) and neither will respond, by losing its signal, to the usual water-wash procedures that are in reality required to clear up the source of the hazardous pollution, i.e. the radio-active material or other hazardous emissions such as war gases, nerve gases, and toxic gases or vapors emitted from poisonous chemicals.